Stanford Swift Education - Very Basic - Refresher

Some useful hints:

Outlet types:

• Outlet
• Action
• Outlet Collection with Index - very useful

Debugger

• lldb: po - print out object
• lldb: p object - formated print out object

Stride

Swift has a helpful stride(), which lets you move from one value to another using any increment – and even lets you specify whether the upper bound is exclusive or inclusive.

stride(from:to:by:) counts from the start point up to by excluding the to parameter. If you want to count up and including the to parameter, you should use stride(from:through:by:)

for i in stride(from: 0, to: 0.5, by: 0.1) {
    print(i)
}

Assert

One level up from print() are assertions, which are debug-only checks that will force your app to crash if a specific condition isn't true.

This is different from print(), which would remain in your code if you shipped it, albeit mostly invisible. In fact, because calls to assert() are ignored in release builds of your app, you can do complex checks:

assert(myReallySlowMethod() == true, "The slow method returned false, which is a bad thing!")

Protocols

Normally any protocol implementor must implement all the methods/properties in the protocol. However, it is possible to mark some methods in a protocol optional.

Any protocol that has optional methods must be marked @objc.

In a class, inits must be marked required (or otherwise a subclass might not conform)